Health experts today warned Brits that plummeting temperatures may raise the likelihood of suffering a debilitating stroke.
Low temperatures have long been known to increase the risks to vulnerable patients including the elderly and those with pre-existing conditions such as respiratory diseases.
But research shows strokes are also more likely during the colder months, with freezing temperatures increasing blood pressure and clotting risks -- key triggers for the potentially fatal condition.
According to the latest forecast, the UK will see temperatures plummet ahead of Christmas with some areas of Scotland seeing lows of -3C.
Arctic air heading to the UK brings with it frosts, ice and snow showers while heavy storms are more likely in southern England and Wales over the festive season.
It also comes days after concerning NHS data showed the ambulances took an average of 42 minutes to respond to category two calls, including strokes, in November.
This is more than twice as long as the 18 minute target.
A fresh MailOnline analysis of health service data earlier this month found strokes among men aged under 39 have jumped by nearly a quarter over the last two decades.
Experts said the delays, coupled with increased winter risks, leaves survivors at greater risk of permanent disability placing further strain on the NHS.
Without prompt treatment a stroke can result in death or long-term disabilities such as paralysis, memory loss and communication problems.
Carolina Fransen, co-founder of Alvica, said: 'The sad reality here is that ambulance delays for strokes can cost lives or people's futures.
'Every minute lost during a stroke is a step closer to irreversible brain damage, yet response times continue to lag as stroke admissions rise.
'It's a double hit -- more people are suffering strokes, and fewer are receiving the timely care they need to maximise their recovery.
'Not only that, but with winter fast approaching the NHS is going to come under even more pressure and research has shown that freezing temperatures can increase the risk of strokes.'
Worryingly, studies also show that heart attacks and strokes are up to twice as likely to happen during cold spells that last four days or more.
This is because the blood vessels narrow in the skin, fingers and toes in response to the cold as the body attempts to preserve heat.
Stroke symptoms are commonly remembered under this four-letter acronym, FAST. Patients experiencing a stroke can often have their face drop on one side, struggle to lift both arms and have slurred speech, while time is essential, as immediate treatment for a transient ischemic attack (TIA) or minor stroke can substantially slash the risk of a much deadlier major stroke
Other - just as common - tell-tale signs of a looming stroke, often fall under the radar. These include sudden numbness on one side of the body, sudden vertigo and difficulty swallowing
This process, called vasoconstriction, raises blood pressure and heart rate, as the heart has to work harder to pump blood around the body.
At the same time, blood becomes thicker and stickier in response when temperatures drop.
This is because the body produces more platelets -- blood cells that form clots to stop bleeding -- in response to the cold, which increases the risk of clotting.
While this is the body's normal response to chilly weather, and a bid to protect vital organs and keep internal temperature at 37C, those with heart conditions are at greater risk.
The British Heart Foundation advises keeping warm by wearing plenty of layers when outside and minimising time spent outdoors when it is especially cold.
One study, published in the European Journal of Epidemiology, also found just how little temperatures need to fall to spark a surge in hospital admissions.
Researchers studied almost 1,700 patients who were admitted to hospital with a stroke between 2003 and 2010 in the town of Jena in Germany.
Every time the thermometer fell by 2.9C (5.2F), stroke risk rose by 11 per cent over the following two days.
Strokes affect more than 100,000 Britons annually -- one every five minutes -- claiming 38,000 lives
When they looked at high-risk patients, they found a 30 per cent increase in the two days after a cold snap.
Strokes affect more than 100,000 Britons annually -- one every five minutes -- claiming 38,000 lives.
This makes it the UK's fourth biggest killer and a leading cause of disability.
Almost 800,000 people in the US are struck down each year, causing 137,000 deaths.
The problem occurs when the blood supply to the brain is cut off, killing brain cells. The damage can lead to long-term disability and affect how people think and feel.
The most common cause is fatty deposits or a blood clot blocking arteries supplying the brain -- known as ischaemic stroke.
This happens due to cardiovascular disease, when blood vessels become narrowed or blocked over time by plaques.
These are made of cholesterol, calcium and other substances that build up in the artery walls in a process known as atherosclerosis.
The other -- called hemorrhagic strokes -- occurs when a blood vessel bursts in the brain and starts to leak its contents into the organ.
It comes as a fresh MailOnline analysis of NHS data earlier this month found strokes among men aged under 39 have jumped by nearly a quarter over the last two decades.
In comparison, life-threatening attacks in women of the same age have risen by just one per cent.
In 2004/05, men under 39 made up 52.8 per cent of cases, compared to 47.2 per cent for women of the same age.
By 2023/24, this gap had widened even further, with men representing nearly two thirds of all cases, while the share of women dropped to 42.3 per cent.
Last month health chiefs also warned of a worrying rise in stroke among the under 50s.
The number of people aged 50 to 59 who suffer the potentially fatal condition has risen by 55 per cent in the past 20 years, official data shows.
Experts said the 'alarming' trends showed that the condition was not just a risk for the elderly, with the rise being fuelled by obesity, stress, poor diet and sedentary lifestyles.
But survival rates have also improved, thanks to medical advances such as the rollout of clot-busting drugs and networks to send patients directly to specialist units.
THE CAUSES OF STROKE
There are two major kinds of stroke:
- ISCHEMIC STROKE
An ischemic stroke - which accounts for 80 per cent of strokes - occurs when there is a blockage in a blood vessel that prevents blood from reaching part of the brain. - HEMORRHAGIC STROKE
The more rare, a hemorrhagic stroke, occurs when a blood vessel bursts, flooding part of the brain with too much blood while depriving other areas of adequate blood supply. It can be the result of an AVM, or arteriovenous malformation (an abnormal cluster of blood vessels), in the brain. Thirty percent of subarachnoid hemorrhage sufferers die before reaching the hospital. A further 25 per cent die within 24 hours. And 40 per cent of survivors die within a week.
RISK FACTORS
- Age
- High blood pressure
- Smoking
- Obesity
- Sedentary lifestyle
- Diabetes
- Atrial fibrillation
- Family history
- History of previous stroke or TIA (mini stroke)
SYMPTOMS OF A STROKE
- Sudden numbness or weakness of the face, arm or leg, especially on one side of the body
- Sudden confusion, trouble speaking or understanding
- Sudden trouble seeing or blurred vision in one or both eyes
- Sudden trouble walking, dizziness, loss of balance or coordination
- Sudden severe headache with no known cause
OUTCOMES
Of the roughly three out of four people who survive a stroke, many will have life-long disabilities.
TREATMENT
Both are potentially fatal, and patients require surgery or a drug called tPA (tissue plasminogen activator) within three hours to save them.